The present invention relates to ribavirin derivatives represented by formula I 
wherein at least one of R2, R3 or R5 is a straight or branched chain polyalkylene oxide polymer conjugate, and pharmaceutical compositions containing them as well as their use to treat patients having susceptible viral infections, alone and in combination with a therapeutically effective amount of interferon-alpha.
Chronic infection with hepatitis C virus is an insidious and slow-progressing disease having a significant impact on the quality of life. It can eventually result in cirrhosis of the liver, decompensated liver disease and/or hepatocelluar carcinoma.
Combination treatment with interferon alfa-2b and ribavirin of patients with chronic hepatitis C is disclosed by Reichard et al.(The Lancet 1998; 351;83-87; and T. Poynard et al.(The Lancet 1998, Vol. 352, October 31, p 1426-1432). See also J. G. McHutchinson et al. (N. EngI. J. Med.,1998, 339:1485-1492); and G. L. Davis et al. (N. Engl. J. Med., 1998, 339:1493-1499). However, this combination therapy is not always effective due to side effects associated ribavirin such as ribavirin-related hemolysis, and anemia.
There is a definite need for more potent, safer ribavirin derivatives having fewer side effects for use as monotherapy or in combination with antiviral agents, e.g., interferon-alpha, to treat patients having suscept-ible viral infections, e.g., chronic hepatitis C infections, in a long-term, effective manner.
The present invention provides a compound represented by formula I 
wherein at least one of R2, R3 or R5 is a straight or branched chain polyalkylene oxide polymer conjugate, and wherein at least one of the remaining of R2, R3 or R5 is H, R6xe2x80x94(W)xxe2x80x94COxe2x80x94, R6xe2x80x94(W)xxe2x80x94CSxe2x80x94, R6xe2x80x94(W)xxe2x80x94Cxe2x95x90NR18xe2x80x94, (HO)2POxe2x80x94, R6xe2x80x94(W)xxe2x80x94PO(OH)xe2x80x94 or HOxe2x80x94SO2xe2x80x94 and wherein at least one of R2, R3 or R5 is not H;
wherein R6 is H, alkyl, alkanoyl, aryl, heterocyclic, cycloalkyl, NR7aR7b, alkenyl, or alkynyl;
or R6 is alkyl, alkanoyl, alkenyl or alkynyl substituted by halo, phenyl, cycloalkyl, NR7aR7b, hydroxy, or alkoxy;
or R6 is aryl substituted by phenyl; halo, CN, NO2, OH, R18, CF3, SH, SR7a, SOR7a, SO2R7a; NR7aR7b, CO2H, CO2xe2x88x92, OR7a, Oxe2x88x92M+ Sxe2x88x92M+ wherein M+ is an alkali metal,
W is O, NR18 or S;
R7a is H, alkyl, alkanoyl, or aryl; or R7a is alkyl, alkanoyl or aryl substituted by phenyl halo, CN, NO2, OH, CO2H, or alkoxy;
and R7b is H, alkyl or aryl or R7b is alkyl or aryl substituted by phenyl halo, CN, NO2, OH, CO2H, or alkoxy;
or R7a and R7b taken together with N and one of CHR7a, NR7a, O, S, SO or SO2 form a five-, six- or seven-membered ring;
R17 is H, OR7a, NR7aR7b, R6xe2x80x94(W)xxe2x80x94COxe2x80x94, R6xe2x80x94(W)xxe2x80x94CSxe2x80x94, R6xe2x80x94(W)xxe2x80x94Cxe2x95x90NR18xe2x80x94, (HO)2POxe2x80x94, R6xe2x80x94(W)xxe2x80x94PO(OH)xe2x80x94 or HOxe2x80x94SO2xe2x80x94;
R18 is H, alkanoyl or alkyl;
and x=0 or 1;
or a pharmaceutically acceptable salt thereof.
The present invention provides a method of treating patients having a susceptible viral infection, such as a chronic hepatitis C infection.
The present invention provides a method of treating patients having comprising administering a therapeutically effective amount of a ribavirin derivative of formula I and a therapeutically effective amount of interferon-alpha for a time period sufficient to eradicate detectable HCV-RNA at the end of said period of administering and to have no detectable HCV-RNA for at least 24 weeks after the end of said period of administrating, and wherein the ribavirin derivative is represented by formula I: 
The present invention also provides a method of treating patients having chronic hepatitis C infection comprising administering a therapeutically effective amount of a ribavirin derivative of formula I and a therapeutically effective amount of interferon-alpha for a time period of at least 20 to 50 weeks to eradicate detectable HCV-RNA at the end of said 20 to 50 week period of administering and to have no detectable HCV-RNA for at least 24 weeks after the end of said period of administrating, and wherein the ribavirin derivative is represented by the formula I: 
The present invention provides a compound represented by formula II 
wherein at least one of R2xe2x80x2, R3xe2x80x2 or R5xe2x80x2 is a straight or branched chain polyalkylene oxide polymer conjugate, and wherein at least one of the remaining of R2xe2x80x2, R3xe2x80x2 or R5xe2x80x2 is a natural or unnatural xcex1-amino acid residue.
In a preferred embodiment, the natural or unnatural xcex1-amino acid residues for the compounds of formula II are represented by the formulas 
Yxe2x95x90H, CH3; CH3CH2xe2x80x94; CH3CH2CH2xe2x80x94; Me2CHxe2x80x94; Me2CH2CH2xe2x80x94; CH3CH2CH(Me)xe2x80x94PhCH2xe2x80x94; HOOCCH2CH2xe2x80x94; HSCH2xe2x80x94; HOOCCH2xe2x80x94; MeSCH2CH2xe2x80x94; HOCH2xe2x80x94; 
or Y is H2N(CH2)4xe2x80x94 or CH3CH(OH)xe2x80x94; or a pharmaceutically acceptable salt thereof;
or Y taken together with the xcex1 carbon and N form 
or a phamaceutically acceptable salt thereof;
or Y taken together with the xcex1 carbon and N form 
or a phamaceutically acceptable salt thereof;
In another embodiment, the present invention relates to a method of treating patients having chronic hepatitis C infection comprising administering a therapeutically effective amount of a ribavirin derivative of formula II and a therapeutically effective amount of interferon-alpha for a time period sufficient to eradicate detectable HCV-RNA at the end of said period of administering and to have no detectable HCV-RNA for at least 24 weeks after the end of said period of administrating, and wherein the ribavirin derivative is represented by formula II 
The present invention also provides a compound represented by formula III 
wherein at least one of R50, R52, R53 is a straight or branched chain polyalkylene oxide polymer conjugate,
and the remaining two of R50, R52, R53 are independently H or a straight or branched chain polyalkylene oxide polymer conjugate,
or a pharmaceutically acceptable salt thereof.
In a preferred embodiment, R52 and R53 in the compounds of Formula III are each H.
The present invention further provides a compound represented by the formula IV 
wherein R50xe2x80x2 is a straight or branched chain polyalkylene oxide polymer conjugate, or a pharmaceutically acceptable salt thereof.
The present invention also provides pharmaceutical compositions for treating susceptible viral infections comprising a compound of formula IV and at least one pharmaceutically acceptable carrier.
The present invention also provides a method of treating a patient with a susceptible viral infection which comprises administering to said patient an effective amount of a compound of formula IV.
The present invention also provides a method of treating a patient infected with chronic hepatitis C which comprises administering to said patient an effective amount of a compound of formula IV in association with an effective amount of an interferon alfa for a time sufficient to eradicate detectable HCV-RNA levels.
The term xe2x80x9calkylxe2x80x9d as used herein means straight and branched carbon chains of one to twenty carbons, preferably one to six carbons and more preferably one to three carbons.
The term xe2x80x9calkenylxe2x80x9d as used herein means straight and branched chain alkyl groups containing at least one carbon-carbon double bond and two to twenty carbons, preferably two to eight carbons.
The term xe2x80x9calkynylxe2x80x9d as used herein means straight and branched chain alkyl groups containing at least one carbon-carbon triple bond and two to twenty carbons, and preferably two to six carbons containing at least one carbon-carbon triple bond.
The term xe2x80x9ccycloalkylxe2x80x9d as used herein means carbocyclic rings of three to twelve carbons, preferably three to seven carbons and more preferably three to six carbons optionally substituted by one double bond.
The term xe2x80x9calkanoylxe2x80x9d as used herein means straight and branched chain alkanoyl groups of one to twenty carbons, preferably two to twelve, more preferably two to ten and most preferably two to six carbons.
The term xe2x80x9calkenoylxe2x80x9d as used herein means straight and branched chain alkenoyl groups of one to twenty carbons containing at least one carbon-carbon double bond, preferably two to twelve, or more preferably two to ten and most preferably two to six carbons containing at least one carbon-carbon double bond.
The term xe2x80x9chaloxe2x80x9d as used herein means fluroro, chloro or bromo, preferably fluroro or chloro.
The term xe2x80x9calkynoylxe2x80x9d as used herein means straight and branched chain alkenoyl groups of one to twenty carbons containing at least one carbon-carbon triple bond, preferably two to twelve, or more preferably two to ten and most preferably two to six carbons containing at least one carbon-carbon triple bond.
The term xe2x80x9calkoxyxe2x80x9d as used herein means straight and branched chain alkyl groups containing one bond to oxygen at the one carbon and one to ten carbons. Typically suitable alkoxy includes methoxy, ethoxy and tert-butoxy.
The term xe2x80x9carylxe2x80x9d as used herein (including the aryl portion of aryloxy and aralkyl, e.g., benzyl)-represents a carbocyclic group containing from 6 to 15 carbon atoms and having at least one aromatic ring (e.g., aryl is a phenyl ring), or is a polycyclic aromatic containing one or more heteroatoms, e.g., N or S such as quinoyl, isoquinolyl with all available substitutable carbon atoms of the carbocyclic group being optionally substituted (e.g., 1 to 3) with one or more of halogen, alkyl, hydroxy, alkoxy, CN, phenoxy, CF3, amino, alkylamino, dialkylamino, SH, Sxe2x88x92M+ or xe2x80x94NO2; and the term xe2x80x9cM+xe2x80x9d represents an alkali metal cation such as Na+, K+ and Li+.
The term xe2x80x9carylalkylxe2x80x9d as used herein means an alkyl group substituted by an aryl group.
The term xe2x80x9cheterocyclicxe2x80x9d as used herein means a cyclic group represented by the formula; 
wherein J is xe2x80x94CHR70xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94NR70xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94 or xe2x80x94SO2xe2x80x94, and I is xe2x80x94CR70 or xe2x80x94Nxe2x80x94; and R70 is H, alkyl or aryl; and h and hxe2x80x2 are indepedently 1 to 4 and the sum of h+hxe2x80x2 is 2, 3, 4 or 5. Typically suitable heterocyclics include 
The term xe2x80x9chaloxe2x80x9d as used herein means fluoro, chloro, bromo or iodo, preferably fluroro or chloro.
The term xe2x80x9cstraight or branched chain polyalkylene oxide polymer conjugatexe2x80x9d as used herein means a (C1-C3)alkoxy polyalkylene oxide polymer having a terminal spacer group (SG). Typically suitable (C1-C3)alkoxy polyalkylene oxide polymers having a terminal spacer group (SG) include.
R7axe2x80x94OCH2CH2xe2x80x94(OCH2CH2)qxe2x80x94SGxe2x80x94,
R7b(OCH2CH2)qxe2x80x94(OCH2)nxe2x80x94SGxe2x80x94,
R7a(OCH2CH2)qxe2x80x94Oxe2x80x94(CH2)txe2x80x94SGxe2x80x94,
R7axe2x80x94O(CH2CH2O)qxe2x80x94CH2CH2xe2x80x94SGxe2x80x94,
R7a(OCH2CH2)qxe2x80x94CH2CH2xe2x80x94SGxe2x80x94, and
m=0 to 100; n=0 to 6000; t=1 to 4; and q=1 to 5000; and SG is as defined hereinbelow.
The (C1-C3)alkoxy polyalkylene oxide conjugates include (C1-C3)alkoxy polyethylene oxide polymer conjugates, especially methoxy-CH2xe2x80x94CH2xe2x80x94(OCH2CH2)jxe2x80x94SG and (C1-C3)alkoxy polypropylene oxide polymer conjugates, especially xe2x80x94(C1-C3)alkoxy C(CH3)Hxe2x80x94CH2xe2x80x94(OC(CH3)HCH2)jxe2x80x94SG. Typically suitable branched-chain polyethylene oxide polymer conjugates include the following 
wherein j and k are independently 400 to 600, preferably each is 420 to 460.
Typically suitable spacer groups (SG) include 
These branched chain polymer conjugates are disclosed in EPO 809 996 and are available from Shearwater Polymers Inc., Huntsville, Ala. Other branched chain polyalkylene oxide conjugates are the methoxy polyethylene glycol conjugates disclosed in U.S. Pat. No. 5,642,575. See especially the examples on col 9, line 38 to col. 13, line 60. Methoxy polyethylene glycols (m-PEG-) are available from Union Carbide Corp., Danbury, Conn. Exemplary methoxy polyethylene glycol conjugates are disclosed in U.S. Pat. No. 5,642,575. Include 
These branched chain polymer conjugates may be prepared in accordance with the procedures of U.S. Pat. No. 5,122,614: using for example methoxy-polyethylene glycol (xe2x80x9cm-PEGxe2x80x9d) having a MW=5000 to form methoxy-poly(ethylene glycol)-N-succinimidyl carbonate (SC-PEG); 
In accordance with the procedures of U.S. Pat. No. 5,642,575., SC-PEG is reacted with 1,3-diamino-2-propanol in an aprotic solvent such as methylene chloride at room temperature to give the compound of the formula A 
The compound of the formula A is treated with an activating group, e.g., p-nitrophenyl chloroformate under anhydrous conditions in the presence of a base such as pyridine to give the activated compound of formula B: 
Reaction of the activated compound of formula B: with benzylidene ribavirin-compound 2 of Example 1 of this invention provides the the branched chain methoxy-polyethylene glycol conjugate of ribavirin of formula III; 
wherein R50 is 
and wherein m-PEG is methoxy-polyethylene glycol.
Typically suitable activating groups include 
wherein R19 is (C1-C6)alkyl or (C3-C8)cycloalkyl, and preferably R1 is methyl; R18 is H, alkanoyl or alkyl and preferably R18 is methyl. See European Patent applications EP 0510356 and EP0236987 for the preparation of the above listed activating groups.
Preferred straight chain polyalkylene oxide polymer conjugates include (C1-C3)alkoxy-polyalkylene oxide polymer especially methoxy-polyethylene glycol conjugates such as wherein j is 400 to 800
In preferred embodiments of the present invention, the compounds of formula I have at least one of R2, R3 and R5 equal to a straight chain polyalkylene oxide polymer conjugate; wherein the straight chain polyalkylene oxide polymer conjugate is selected from
R7axe2x80x94OCH2CH2(OCH2CH2)qxe2x80x94(W)xxe2x80x94COxe2x80x94,
R7b(OCH2CH2)qxe2x80x94(OCH2)nxe2x80x94(W)xxe2x80x94COxe2x80x94,
R7a(OCH2CH2)qxe2x80x94Oxe2x80x94(CH2)txe2x80x94C(xe2x95x90NR18)xe2x80x94
R7bOOCxe2x80x94(CH2)mxe2x80x94[CR7a(OR7a)]nxe2x80x94(W)xxe2x80x94COxe2x80x94,
R7axe2x80x94O(CH2CH2O)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94COxe2x80x94
R7axe2x80x94O(CH2CH2O)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94C(xe2x95x90NR18)xe2x80x94
R7bOOCxe2x80x94(CH2)mxe2x80x94(OCHR7a)nxe2x80x94(W)xxe2x80x94COxe2x80x94, or
R7a(OCH2CH2)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94COxe2x80x94
R7a(OCH2CH2)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94C(xe2x95x90NR18)xe2x80x94; or
W=xe2x80x94Oxe2x80x94 or xe2x80x94NR18xe2x80x94; and R18xe2x95x90H;
m=0 to 100; n=0 to 6000; t=1 to 4; and q=1 to 5000.
In another preferred embodiment of the present invention, the compounds of formula I have R2xe2x95x90R3xe2x95x90H and R5 is one of the above listed straight chain polyalkylene oxide polymer conjugates.
In another preferred embodiments of the present invention, the compounds of formula II have at least one of R2xe2x80x2, R3xe2x80x2 and R5xe2x80x2 equal to a straight chain polyalkylene oxide polymer conjugate; wherein the straight chain polyalkylene oxide polymer conjugate is selected from
R7axe2x80x94OCH2CH2(OCH2CH2)qxe2x80x94(W)xxe2x80x94COxe2x80x94;
R7b(OCH2CH2)qxe2x80x94(OCH2)nxe2x80x94(W)xxe2x80x94COxe2x80x94,
R7axe2x80x94(OCH2CH2)qxe2x80x94Oxe2x80x94CH2)txe2x80x94C(xe2x95x90NR18)xe2x80x94
R7axe2x80x94O(CH2CH2O)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94COxe2x80x94
R7axe2x80x94O(CH2CH2O)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94C(xe2x95x90NR18)xe2x80x94
R7b(OCH2CH2)qxe2x80x94(OCH2)nxe2x80x94(W)xxe2x80x94COxe2x80x94,
R7bOOCxe2x80x94(CH2)m[CR7a(OR7a)]nxe2x80x94(W)xxe2x80x94COxe2x80x94,
R7bOOCxe2x80x94(CH2)mxe2x80x94(OCHR7a)nxe2x80x94(W)xxe2x80x94COxe2x80x94 or
R7a(OCH2CH2)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94COxe2x80x94; or
R7a(CH2CH2)qxe2x80x94CH2CH2xe2x80x94(W)xxe2x80x94C(xe2x95x90NR18)xe2x80x94; and
W=xe2x80x94Oxe2x80x94 or xe2x80x94NR18xe2x80x94; and R18xe2x95x90H;
and m=0 to 100; n=0 to6000; q=1 to 5000; t=1 to 4; and x=0 or 1.
In another preferred embodiment of the present invention, the compounds of formula II have R2xe2x80x2=R3xe2x80x2xe2x95x90H and R5xe2x80x2 is one of the above listed straight chain polyalkylene oxide polymer conjugates.
In more preferred embodiments of the present invention, (a) wherein the compounds of formula I have R2xe2x95x90R3xe2x95x90H and (b) wherein the compounds of formula II have R2xe2x95x90R3xe2x95x90H, R5 and R5xe2x80x2 are independently one of the following preferred straight chain polyalkylene oxide polymer conjugates:
R7bxe2x80x94OOCxe2x80x94CH2(OCH2CH2)qxe2x80x94OCH2COxe2x80x94, R7axe2x80x94OCH2CH2(OCH2CH2)qOCH2COxe2x80x94
R7b(OCH2CH2)qxe2x80x94(OCH2)nxe2x80x94COxe2x80x94, R7axe2x80x94OCH2CH2(OCH2CH2)qxe2x80x94NHxe2x80x94COxe2x80x94;
R7axe2x80x94OCH2CH2(OCH2CH2)qxe2x80x94Oxe2x80x94COxe2x80x94; R7axe2x80x94O(CH2CH2O)qxe2x80x94CH2CH2xe2x80x94NHxe2x80x94COxe2x80x94;
R7axe2x80x94O(CH2CH2)qxe2x80x94CH2CH2xe2x80x94NHxe2x80x94C(xe2x95x90NR18)xe2x80x94;
R7a(OCH2CH2)qxe2x80x94CH2CH2xe2x80x94NHxe2x80x94C(xe2x95x90NH)xe2x80x94; or
R7b(OCH2CH2)qxe2x80x94(OCH2)nxe2x80x94COxe2x80x94; and
n=0 to 6000; and q=1 to 5000.
Examplary methoxy-polyethylene glycol conjugates include 
The methoxy-polyethylene glycol conjugates can readily be prepared and their molecular weight determined by one skilled in the art view of known methods such as described in European Patent Applications EP0236987 and EP0510356. The starting polyethylene glycols (PEG) and PEG monomethyl ethers of various molecular weights e.g. 750, 1900, 5000, 10,000 can readily be prepared by methods known in the art or can be obtained from commercial sources.
In a preferred embodiment of the present invention, compounds of formula I have R2xe2x95x90R3xe2x95x90H and R5 equal to R6(W)xCOxe2x80x94, (HO)2Pxe2x95x90Oxe2x80x94 or R6(W)xPO(OH)xe2x80x94. In the preferred embodiments of R6xe2x80x94(W)xCOxe2x80x94 and R6(W)xxe2x80x94PO(OH)xe2x80x94, Wxe2x95x90O or NH and x=0 or 1. In other preferred embodiments of R6xe2x80x94(W)xCOxe2x80x94 and R6(W)xP(OH)Oxe2x80x94 include R17(CH2)mxe2x80x94NR7bR7axe2x80x94(CH2)nOCOxe2x80x94 and R17(CH2)mxe2x80x94NR7bR7axe2x80x94(CH2)nxe2x80x94Oxe2x80x94PO(OH), wherein m=0 to 4 N=0 to 4; and R17 is H, Me, MeCOxe2x80x94 or Me2Nxe2x80x94, and R7aR7bN(CH2)fxe2x80x94(CHR7a)eOCOxe2x80x94 or R7aR7bN (CH2)fxe2x80x94(CHR7a)eCOxe2x80x94;wherein f=0 to 4 and e=1 to 5, and R7aR7bN is Me2Nxe2x80x94, MeHNxe2x80x94 or MeCONHxe2x80x94.
In most preferred embodiments of of the compounds of formula I, x in R6(W)xCOxe2x80x94, is equal to 0.
In another preferred embodiment of the compounds of formula I, one of R2, R3 or R5. is R6CO and R6CO is a natural or unnatural xcex1-amino acid residue.
In another preferred embodiment of the compounds of formula II, one of R2xe2x80x2, R3xe2x80x2 or R5xe2x80x2. is a natural or unnatural xcex1-amino acid residue.
The term xe2x80x9ca natural or unnatural xcex1-amino acid residuexe2x80x9d as used herein means a residue represented by the formula 
wherein Q is 
wherein R61 and R62 are independently H, alkyl, alkenyl, alkynyl, (C3-C7)cycloalkyl, arylalkyl, or alkyl, alkenyl, alkynyl, (C3-C7)cycloalkyl, arylalkyl, substituted by halo, OH, SH, CF3, SR67, OR67 or NR65R66 or wherein R61 and R62 taken together with the carbon atom in (CR61R62) form a cyclopropane, cyclobutane, cyclopentane, or cyclohexane;
wherein R63 and R64 are independently H, alkanoyl, alkyl, aryl, arylalkyl, alkenyl, alkynyl, or alkanoyl, alkyl, aryl, arylalkyl, alkenyl, alkynyl substituted by halo, OH, SH, CF3, SR67, OR67; or R63 and R64 are independently 
wherein R67 is H, alkyl, alkanoyl, alkenoyl, aryl, arylalkyl, alkenyl, alkynyl, or, alkyl, aryl, arylalkyl, alkenyl, alkynyl substituted by halo, OH, SH, CF3, alkanoylthienyl, or alkanoyloxy;
wherein R68 is H, alkyl, aryl, arylalkyl, alkenyl, or alkynyl; and g is 0, 1 or 2; d is 1 or 2;
In a more preferred embodiments of the compounds of formulas I and II, the preferred natural or unnatural xcex1-amino acid residues are selected from 
wherein Yxe2x95x90H, CH3; CH3CH2xe2x80x94; CH3CH2CH2xe2x80x94; Me2CHxe2x80x94; Me2CH2CH2xe2x80x94; CH3CH2CH(Me)xe2x80x94PhCH2xe2x80x94; HOOCCH2CH2xe2x80x94; HSCH2xe2x80x94; HOOCCH2xe2x80x94; MeSCH2CH2xe2x80x94; HOCH2xe2x80x94; 
or Y is H2N(CH2)4xe2x80x94 or CH3CH(OH)xe2x80x94; or a pharmaceutically acceptable salt thereof;
or Y taken together with the a carbon and N form 
or a pharmaceutically acceptable salt thereof.
or 
wherein R7a is as defined hereinabove; or a pharmaceutically acceptable salt thereof.
In another more preferred embodiment of the compounds of formulas I and II, the preferred natural xcex1-amino acid residues are selected from 
Yxe2x95x90H, CH3; CH3CH2xe2x80x94; CH3CH2CH2xe2x80x94; Me2CHxe2x80x94; Me2CH2CH2xe2x80x94; CH3CH2CH(Me)xe2x80x94PhCH2xe2x80x94; HOOCCH2CH2xe2x80x94; HSCH2xe2x80x94; HOOCCH2xe2x80x94; MeSCH2CH2xe2x80x94; HOCH2xe2x80x94; 
Y is H2N(CH2)4xe2x80x94 or CH3CH(OH)xe2x80x94; or a pharmaceutically b acceptable salt thereof
or Y taken together with the a carbon and N form 
wherein R7a is as defined hereinabove;
or a pharmaceutically acceptable salt thereof.
Other preferred embodiments for R6CO in the compounds of formula I include 
(CH3)3COxe2x80x94, C6H5COxe2x80x94,(HO)2POxe2x80x94 and
Lxe2x80x94C6H5CH2OCONHCH(CH3)COxe2x80x94, i.e., C6H5CH2OCONHCH
or R6CO is 
or a pharmaceutically acceptable salt thereof;
wherein Ph is phenyl and phenyl substituted by halo, CN, NO2, OH, CO2H, or alkoxy.
The most preferred natural or unnatural amino acid residues in the compounds of formulas I and II are represented by the formulas in Table AA herein below:
The compounds of formulas I to IV metabolize in vivo into ribavirin and are useful for treating susceptible viral infections treatable with ribavirin, alone, or in combination with other ant-viral therapies eg., interferon-alfa, and so-called Highly Active Antiretroviral Therapy (xe2x80x9cHAARTxe2x80x9d). A-M. Vandamme et al., Antiviral Chemistry and Chemotherapy, 9:187-203 (1998) disclose current clinical treatments of HIV-1 infections in man including at least triple drug combinations or so-called Highly Active Antiretroviral Therapy (xe2x80x9cHAARTxe2x80x9d); HAART involves various combinations of nucleoside reverse transcriptase inhibitors (xe2x80x9cNRTIxe2x80x9d), non-nucleoside reverse trans-criptase inhibitors (xe2x80x9cNNRTIxe2x80x9d) and HIV protease inhibitors (xe2x80x9cPIxe2x80x9d). The treating of patients having chronic hepatitis C with the compounds of formulas I-VIII is performed as part of a combination therapy with interferon-alfa, including interferon alfa-2a, interferon alfa-2b, consensus interferon especially interferon alfa-2b as well as pegylatyed interferon alfa-2a and pegylatyed interferon alfa-2b.
The present invention provides methods and pharmaceutical compositions containing a compound of formulas I-IV for treating susceptible viral infections, especially hepatitis C viral infections.
The term xe2x80x9csusceptible viral infectionsxe2x80x9d as used herein means viral infections caused by a wide range of RNA and DNA viruses, including, but not limited to, the families of viruses such as flaviruses-including the genus flavirus, pestivirus of which Kunjin virus is a member, and hepavirus of which hepatitis C virus is a member, and arbovirus of which the West Nile virus is a member-orthomyxoviruses, paramyxoviruses, arenaviruses, bunyaviruses, herpes viruses, adenoviruses, poxyiruses, and retroviruses.
Typical suitable xe2x80x9csusceptible viral infectionsxe2x80x9d include influenza A and B viral infections; parainfluenza viral infections, respiratory syncytial virus (xe2x80x9cRSVxe2x80x9d) infections such as RSV bronchiolitis and RSV pneumonia especially such RSV infections in children and infants as well as RSV pneumonia in patients with preexisting cardiopulmonary disease, measles viral infections, Lassa fever viral infections, Korean Haemorrhagic fever infections, hepatitis B viral (HBV) infections, Crimean.Congo-Haemorrhagic and HCV infections and HIV-1 infections, encephalitis infections such as caused by West Nile virus or Kunjin virus or the St. Louis encephalitis infections as well as viral infections found in immunocompromised patients. Other susceptible viral infections are disclosed in U.S. Pat. No. 4,211,771 at column 2, line 21 to column 3 line 37; doses and dose regimens and formulations are disclosed at column 3, line 4 to column 9, line 5; see also Canadian Patent No. 1,261, 265. Sidwell, R. W., et al. Pharmacol. Ther., 1979, Vol 6 pp 123-146 discloses that the in vivo antiviral experiments conducted with ribavirin generally confirm one broad-spectrum antiviral activity seen in vitro and states that the efficacy of ribavirin is quite dependent upon the site of infection; the manner of treatment; the age of the animal and the virus dosage utilized. Tables 4 and 5 on page 127 list the RNA and DNA virus infections significantly inhibited in vivo by ribavirin.
The in vitro inhibitory concentrations of ribavirin are disclosed in Goodman and Gilman""s xe2x80x9cThe Pharmacological Basis of Therapeuticsxe2x80x9d, Ninth Edition, (1996) McGraw Hill, New York, at pages 1214-1215. The Virazole product information discloses a dose of 20 mg/mL of Virazole aerosol for 18 hours exposure in the 1999 Physicians Desk Reference at pages 1382-1384.
Ribavirin dosage and dosage regimens are also disclosed by Sidwell, R. W., et al. Pharmacol. Ther 1979 Vol 6. pp123-146 in section 2.2 pp 126-130. Fernandes, H., et al., Eur. J. Epidemiol., 1986, Vol 2(1) pp1-14 at pages 4-9 disclose dosage and dosage regimens for oral, parenteral and aerosol administration of ribavirin in various preclinical and clinical studies.
The term xe2x80x9cpatients having hepatitis C infectionsxe2x80x9d as used herein means any patient-including a pediatric patient having hepatitis C and includes treatment-naive patients having hepatitis C infections and treatment-experienced patients having hepatitis C infections as well as those pediatric, treatment-naive and treatment-experienced patients having chronic hepatitis C infections.
These patients having hepatitis C include those who are infected with multiple HCV genotypes including type 1 as well as those infected with, e.g., HCV genotypes 2, 3, 4, 5 and/or 6 and other possible HCV genotypes.
The term xe2x80x9ctreatment-naive patients having hepatitis C infectionsxe2x80x9d as used herein means patients with hepatitis C who have never been treated with ribavirin or any interferon, including but not limited to interferon-alfa, or pegylated interferon alfa.
The term xe2x80x9ctreatment-experienced patients having hepatitis C infectionsxe2x80x9d as used herein means patients with hepatitis C who have been treated with ribavirin or any interferon, including but not limited to interferon-alfa, or pegylated interferon alfa, including relapsers and non-responder.
The term xe2x80x9crelapsersxe2x80x9d as used herein means treatment-experienced patients with hepatitis C who have relapsed after initial response to previous treatment with interferon alone, or in combination with ribavirin.
The term xe2x80x9cnon-respondersxe2x80x9d as used herein means treatment-experienced patients with hepatitis C who have not responded to prior treatment with any interferon alone, or in combination with ribavirin.
When the pegylated interferon-alfa administered is a pegylated interferon alfa-2b, the therapeutically effective amount of pegylated interferon alfa-2b administered during the treatment in accordance with the present invention, including in first and second treatment time periods, is in the range of about 0.1 to 9.0 micrograms per kilogram of pegylated interferon alfa-2b administered per week, in single or divided doses, preferably once a week (QW) or twice a week (BIW), preferably in the range of about 0.1 to about 9.0 micrograms per kilogram of pegylated interferon alfa-2b administered once a week (QW) or in the range of about 0.05 to about 4.5 micrograms per kilogram of pegylated interferon alfa-2b administered twice a week (BIW), or is in the range of about 0.5 to about 3.0 micrograms per kilogram of pegylated interferon alfa-2b administered per week, preferably in the range of about 0.5 to about 3.0 micrograms per kilogram of pegylated interferon alfa-2b administered once a week (QW) or in the range of about 0.25 to about 1.5 micrograms per kilogram of pegylated interferon alfa-2b administered twice a week, or is in the range of about 0.75 to about 1.5 micrograms per kilogram of pegylated interferon alfa-2b administered per week, most preferably is in the range of about 0.75 to about 1.5 micrograms per kilogram of pegylated interferon alfa-2b administered once a week or about 0.375 to about 0.75 micrograms per kilogram of pegylated interferon alfa-2b administered twice a week.
When the pegylated interferon-alfa administered to pediatric patients is a pegylated interferon alfa-2b, the therapeutically effective amount of pegylated interferon alfa-2b administered during the treatment in accordance with the present invention is in the range of about 0.1 to 9.0 micrograms per kilogram of pegylated interferon alfa-2b administered per week, in single or divided doses, preferably once a week (QW) or twice a week (BIW), more preferably about 0.1 to about 9.0 micrograms per kilogram of pegylated interferon alfa-2b administered once a week (QW), or about 0.05 to about 4.5 micrograms per kilogram of pegylated interferon alfa-2b administered per week, in single or divided doses, preferably once a week (QW) or twice a week (BIW), more preferably about 0.05 to about 4.5 micrograms per kilogram of pegylated interferon alfa-2b administered once a week, or preferably about 0.75 to about 3.0 micrograms per kilogram of pegylated interferon alfa-2b administered in single or divided doses, preferably once a week (QW) or twice a week (BIW), more preferably about 0.75 to about 3.0 micrograms per kilogram of pegylated interferon alfa-2b administered once a week or about 0.375 to about 1.5 micrograms per kilogram of pegylated interferon alfa-2b administered twice a week, and most preferably about 2.25 to about 2.6 micrograms per kilogram of pegylated interferon alfa-2b administered once a week or about 1.1 to about 1.3 micrograms per kilogram of pegylated interferon alfa-2b administered twice a week (BIW).
When the pegylated interferon-alfa administered is a pegylated interferon alfa-2a, the therapeutically effective amount of pegylated interferon alfa-2a administered in accordance with the present invention, is in the range of about 50 micrograms to about 500 micrograms once a week (xe2x80x9cQWxe2x80x9d), preferably about 150 micrograms to about 250 micrograms QW or the effective amount is in the range of about 50 micrograms to about 250 micrograms twice a week, preferably about 100 micrograms to about 125 micrograms twice a week.
When the pegylated interferon-alfa administered to a pediatric patient is a pegylated interferon alfa-2a, the therapeutically effective amount of pegylated interferon alfa-2a administered in accordance with the present invention, is in the range of about 50 micrograms to about 500 micrograms once a week (xe2x80x9cQWxe2x80x9d), preferably about 300 micrograms to about 375 micrograms QW or the therapeutically effective amount of pegylated interferon alfa-2a administered to a pediatric patient is in the range of about 50 micrograms to about 250 micrograms twice a week, preferably about 150 micrograms to about 190 micrograms once a week
The esters of ribavirin represented by formulas I-IV are administered to the patient having chronic HCV in association with pegylated interferon-alfa, that is, before, after or concurrently with the administration of the pegylated interferon alfa. The pegylated interferon-alfa dose is preferably administered during the same period of time that the patient receives doses of esters of ribavirin represented by formulas I-IV. The amount of esters of ribavirin represented by formulas I-IV administered concurrently with the pegylated interferon-alfa is from about 200 to about 1600 mg per day, preferrably about 300 to about 1200 mg/day or about 400 to about 800 mg day and most preferably about 400 to about 600 mg a day. The pegylated interferon-alfa dose is also preferably administered to the pediatric patient during the same period of time that such patient receives doses of the esters of ribavirin represented by formulas I-IV. The amount of the 5xe2x80x2-amino acid esters of ribavirin represented by formulas I-IV administered to the pediatric patient having chronic HCV concurrently with the interferon-alfa is from about 1 to about 30 mg per kilogram per day, preferrably from about 4 to about 15 mg per kilogram per day, more preferrably about 6, 8 or 15 mg per kilogram per day, most preferrably about 8 to 10 mg per kilogram per day in divided doses.
Pegylated interferon-alfa formulations are not effective when administered orally, so the preferred method of administering the pegylated interferon-alfa is parenterally, preferably by sub-cutaneous (SC), intravenous (IV), or intramuscular (IM) injection. The compounds represented by formulas I-IV may be administered orally in capsule, tablet, or liquid form, intranasally as an aerosol by nasal spray or parenterally, preferably by SC, IV, or IM injection. The esters of ribavirin represented by formulas I-IV may be orally administered in association with the parenteral administration of pegylated interferon-alfa. Of course, other types of administration of both medicaments, as they become available, are contemplated, such as transdermally, by suppository, by sustained release dosage form, and by pulmonary inhalation. Any form of administration will work so long as the proper dosages are delivered without destroying the active ingredient.
The term xe2x80x9cinterferon-alfaxe2x80x9d as used herein means the family of highly homologous species-specific proteins that inhibit viral replication and cellular proliferation and modulate immune response. Typical suitable interferon-alfas include, but are not limited to, recombinant interferon alfa-2b, such as Intron-A interferon available from Schering Corporation, Kenilworth, N.J., recombinant interferon alfa-2a, such as Roferon interferon available from Hoffmann-La Roche, Nutley, N.J., recombinant interferon alpha-2c, such as Berofor alpha 2 interferon available from Boehringer Ingelheim Pharmaceutical, Inc., Ridgefield, Conn., interferon alpha-n1, a purified blend of natural alfa interferons, such as Sumiferon available from Sumitomo, Japan or as Wellferon interferon alpha-ni (INS) available from the Glaxo-Wellcome Ltd., London, Great Britain, or a consensus alpha interferon, such as those described in U.S. Pat. Nos. 4,897,471 and 4,695,623 (especially Examples 7, 8 or 9 thereof) and the specific product available from Amgen, Inc., Newbury Park, Calif., or interferon alfa-n3 a mixture of natural alfa interferons made by Interferon Sciences and available from the Purdue Frederick Co., Norwalk, Conn., under the Alferon Tradename. The use of interferon alfa-2a or alpha 2b is preferred. Since interferon alpha 2b, among all interferons, has the broadest approval throughout the world for treating chronic hepatitis C infection, it is most preferred. The manufacture of interferon alpha 2b is described in U.S. Pat. No. 4,530,901.
The term xe2x80x9cpegylated interferon alfaxe2x80x9d as used herein means polyethylene glycol modified conjugates of interferon alfa, preferably interferon alfa-2a and -2b. The preferred polyethylene-glycol-interferon alfa-2b conjugate is PEG12000-interferon alfa 2b. The phrases xe2x80x9c12,000 molecular weight polyethylene glycol conjugated interferon alphaxe2x80x9d and xe2x80x9cPEG12000-IFN alfaxe2x80x9d as used herein mean conjugates such as are prepared according to the methods of International Application No. WO 95/13090 and containing urethane linkages between the interferon alfa-2a or -2b amino groups and polyethylene glycol having an average molecular weight of 12000.
The preferred PEG12000-interferon alfa-2b is prepared by attaching a PEG polymer to the epsilon amino group of a lysine residue in the IFN alfa-2b molecule. A single PEG12000 molecule is conjugated to free amino groups on an IFN alfa-2b molecule via a urethane linkage. This conjugate is characterized by the molecular weight of PEG12000 attached. The PEG12000-IFN alfa-2b conjugate is formulated as a lyophilized powder for injection. The objective of conjugation of IFN alfa with PEG is to improve the delivery of the protein by significantly prolonging its plasma half-life, and thereby provide protracted activity of IFN alfa.
Other pegylated interferon alfa conjugates can be prepared by coupling an interferon alfa to a water-soluble polymer. A non-limiting list of such polymers include other polyalkylene oxide homopolymers such as polypropylene glycols, polyoxyethylenated polyols, copolymers thereof and block copolymers thereof. As an alternative to polyalkylene oxide-based polymers, effectively non-antigenic materials such as dextran, polyvinylpyrrolidones, polyacrylamides, polyvinyl alcohols, carbohydrate-based polymers and the like can be used. Such interferon alfa-polymer conjugates are described in U.S. Pat. Nos. 4,766,106, 4,917,888, European Patent Application No. 0 236 987, European Patent Application Nos. 0510 356, 0 593 868 and 0 809 996 (pegylated interferon alfa-2a) and International Publication No. WO 95/13090.
Pharmaceutical composition of pegylated interferon alfa suitable for parenteral administration may be formulated with a suitable buffer, e.g., Tris-HCl, acetate or phosphate such as dibasic sodium phosphate/monobasic sodium phosphate buffer, and pharmaceutically acceptable excipients, e.g., sucrose, carriers, e.g., humanor recombinant plasma albumin, tonicity agents, e.g. NaCl, preservatives, e.g., thimerosol, cresol or benyl alcohol, and surfactants, e.g., tweens or polysorabates in sterile water for injection. The pegylated interferon alfa-may be stored as lyophilized powders under a refrigeration at 2xc2x0-8xc2x0 C. The reconstituted aqueous solutions are stable when stored between 2xc2x0 and 8xc2x0 C. and used within 24 hours of reconstitution. See for example U.S. Pat. Nos. 4,492,537; 5,762,923 and 5,766,582. The reconstituted aqueous solutions may also be stored in prefilled, multi-dose syringes such as those useful for delivery of drugs such as insulin. Typical suitable syringes include systems comprising a prefilled vial attached to a pen-type syringe such as the NOVOLET Novo Pen available from Novo Nordisk, as well as prefilled, pen-type syringes which allow easy self-injection by the user. Other syringe systems include a pen-type syringe comprising a glass cartridge containing a diluent and lyophilized pegylated interferon alfa powder in a separate compartment.
A person suffering from chronic hepatitis C infection may exhibit one or more of the following signs or symptoms:
(a) elevated ALT,
(b) positive test for anti-HCV antibodies,
(c) presence of HCV as demonstrated by a positive test for the presence of HCV-RNA in the serum,
(d) clinical stigmata of chronic liver disease,
(e) hepatocelluar damage.
The combination therapy of pegylated interferon-alfa and the esters of ribavirin represented by formulas I-IV may also be administered in association with anti-retroviral therapy, e.g., HAART, to the patient co-infected with the HIV-1 and HCV infection and exhibiting one or more of the above signs or symptoms in amounts sufficient to eliminate or at least alleviate one or more of the signs or symptoms of hte HCV infection, and to lower the HIV-1-RNA and HCV-RNA serum levels each by at least a power of ten, and preferably to eradicate detectable HCV-RNA at least by the end of about 20 to about 50 weeks, preferably at least 24 weeks to 48 weeks and to maintain no detectable HCV-RNA for at least 24 weeks after the end of the about 20 to about 50 weeks. Administration of the compounds represented by formulas I-IV may be discontinued after the end of the second time period depending upon the judgment of the attending clinician.
The term xe2x80x9cno detectable HCV-RNAxe2x80x9d in the context of the present invention means that there are fewer than 100 copies of HCV-RNA per ml of serum of the patient as measured by quantitative, multi-cycle reverse transcriptase PCR methodology. HCV-RNA is preferably measured in the present invention by research-based RT-PCR methodology well known to the skilled clinician. This methodology is referred to herein as HCV-RNA/qPCR. The lower limit of detection of HCV-RNA is 100 copies/mL. Serum HCV-RNA/qPCR testing and HCV genotype testing will be performed by a central laboratory. See also J. G. McHutchinson et al. (N. Engl. J. Med., 1998, 339:1485-1492), and G. L. Davis et al. (N. Engl. J. Med. 339:1493-1499).
For preparing pharmaceutical compositions from the compounds described by this invention, inert, pharmaceutically acceptable carriers can be either solid or liquid. Solid form preparations include powders, tablets, dispersible granules, capsules, cachets and suppositories. The powders and tablets may be comprised of from about 5 to about 95 percent active ingredient. Suitable solid carriers are known in the art, e.g. magnesium carbonate, magnesium stearate, talc, sugar or lactose. Tablets, powders, cachets and capsules can be used as solid dosage forms suitable for oral administration. Examples of pharmaceutically acceptable carriers and methods of manufacture for various compositions may be found in A. Gennaro (ed.), Remington""s Pharmaceutical Sciences, 18th Edition, (1990), Mack Publishing Co., Easton, Pa.
Liquid form preparations include solutions, suspensions and emulsions. As an example may be mentioned water or water-propylene glycol solutions for parenteral injection or addition of sweeteners and opacifiers for oral solutions, suspensions and emulsions. Liquid form preparations may also include solutions for intranasal administration.
Aerosol preparations suitable for inhalation may include solutions and solids in powder form, which may be in combination with a pharmaceutically acceptable carrier, such as an inert compressed gas, e.g. nitrogen.
Also included are solid form preparations that are intended to be converted, shortly before use, to liquid form preparations for either oral or parenteral administration. Such liquid forms include solutions, suspensions and emulsions.
The compounds of the invention may also be deliverable transdermally. The transdermal compositions can take the form of creams, lotions, aerosols and/or emulsions and can be included in a transdermal patch of the matrix or reservoir type as are conventional in the art for this purpose.
Preferably the compound is administered orally.
Preferably, the pharmaceutical preparation is in a unit dosage form. In such form, the preparation is subdivided into suitably sized unit doses containing appropriate quantities of the active component, e.g., an effective amount to achieve the desired purpose.
The quantity of active compound in a unit dose of preparation may be varied or adjusted from about 0.01 mg to about 1000 mg, preferably from about 0.01 mg to about 750 mg, more preferably from about 0.01 mg to about 500 mg, and most preferably from about 0.01 mg to about 250 mg, according to the particular compound and particular application.
The actual dosage employed may be varied depending upon the requirements of the patient and the severity of the condition being treated. Determination of the proper dosage regimen for a particular situation is within the skill of the art. For convenience, the total daily dosage may be divided and administered in portions during the day as required.
The amount and frequency of administration of the compounds of the invention and/or the pharmaceutically acceptable salts thereof will be regulated according to the judgment of the attending clinician considering such factors as age, condition and size of the patient as well as severity of the symptoms being treated. A typical recommended daily dosage regimen for oral administration can range from about 1 mg/kg/day to about 100 mg/kg/day, in two to four divided doses.
In a preferred embodiment of the present invention, those patients co-infected with HIV-1 and HCV infections are treated with pegylated interferon alfa in combination with the preferred 5xe2x80x2-amino acid esters of ribavirin represented by formulas III to VIII and a HAART combination considered appropriate by the attending clinician and the patient. See also J. G. McHutchinson et al. (N. Engl. J. Med., 1998, 339:1485-1492), and G. L. Davis et al. (N. Engl. J. Med. 1998, 339:1493-1499).
The preferred compounds of formulas I-IV are useful for treating patients having suceptible viral infections, e.g., chronic hepatitis C. The compounds of formulas III-VIII metabolize in vivo into ribavirin and are useful for treating susceptible viral infections treatable with ribavirin, alone, or in combination with other anti-viral therapies, e.g., interferon-alfa and HAART. The treating of patients having chronic hepatitis C with the compounds of formulas I-IV is performed as part of a combination therapy with interferon-alfa, especially interferon alfa-2b.
Compounds of formulas I-IV metabolize in vivo into ribavirin and produce higher plasma concentrations of ribavirin after oral administration of a compound of formulas I-IV to animals compared to administration of ribavirin.
The pharmaceutical compositions of the esters of ribavirin of the present invention (represented by formulas III and IV) may be adapted for any mode of administration e.g., for oral, parenteral, e.g., subcutaneous (xe2x80x9cSCxe2x80x9d), intramuscular (xe2x80x9cIMxe2x80x9d), intravenous (xe2x80x9cIVxe2x80x9d) and intraperitoneal (xe2x80x9cIPxe2x80x9d), topical or vaginal administration or by inhalation (orally or intranasally). Preferably the ribavirin compounds represented by formula I are administered orally.
Such compositions may be formulated by combining a compound of formulas I-IV or an equivalent amount of a pharmaceutically acceptable salt of compound I with an suitable, inert, pharmaceutically acceptable carrier or diluent which may be either solid or liquid. The compounds of formulas I-IV are preferably converted into the pharmaceutically acceptable acid addition salts by adding to compounds of formulas I-IV an equivalent amount (or two equivalents in the case of for example the lysine ester) of a pharmaceutically acceptable acid. Typically suitable pharmaceutically aceptable acids include the mineral acids, e.g., HNO3H2SO4, H3PO4, HCl, HBr, organic acids, including, but not limited to, acetic, trifluoroacetic, propionic, lactic, maleic, succinic, tartaric, glucuronic and citric acids as well as alkyl or arylsulfonic acids, such as p-toluenesulfonic acid, 2-naphthalenesulfonic acid, or methanesulfonic acid.
Typically suitable pharmaceutically acceptable salts include the following anions: acetate, adipate, besylate (benzenesulfonate), bromide, camsylate[(+)-7,7-dimethyl-2-oxobicyclo[2.2.1]hepatane-1-methanesulfonate], chloride, citrate, edisylate(1,2-ethanedisulfonate), estolate(dodecyl sulfate), fumarate, gluceptate(glucoheptonate), gluconate, glucuronate, hippurate, hyclate(hydrochloride, hemiethanolate), hydrobromide, hydrochloride, iodide, isethionate (2-hydroxyethanesulfonate), lactate, lactobionate, maleate, mesylate (methanesulfonate), methylbromide, methylsulfate, napsylate, nitrate, oleate, pamoate [4,4xe2x80x2-methylenebis[3-hydroxy-2-napthalene-carboxylate]], phosphate, polygalacturonate, stearate, succinate, sulfate, sulfosalicylate, tannate, tartrate, terephthalate, tosylate(p-toluenesulfonate), triethiodide;
and the following catrons:
benzathine (N,N-bis(phenylmethyl)-1,2-ethanediamine), calcium, diolamine (2,2-iminobis(ethanol), meglumine[1-deoxy-1-(methylamino)-D-glucitol], olamine(2-aminoethanol), potassium, procaine, sodium tromethamine [2-amino-2-(hydroxymethyl)-1,3 propanediol,] and zinc.
The preferred pharmaceutically acceptable salts are trifluoroacetate, tosylate, mesylate, and chloride.
Solid form preparations include powders, tablets, dispersible granules, capsules, cachets and suppositories. The powders and tablets may be comprised of from about 5 to about 95 percent active ingredient. Suitable solid carriers are known in the art, e.g. magnesium carbonate, magnesium stearate, talc, sugar or lactose. Tablets, powders, cachets and capsules can be used as solid dosage forms suitable for oral administration. Examples of pharmaceutically acceptable carriers and methods of manufacture for various compositions may be found in A. Gennaro (ed.), Remington""s Pharmaceutical Sciences, 18th Edition, (1990), Mack Publishing Co., Easton, Pa.
Liquid form preparations include solutions, suspensions and emulsions. As an example may be mentioned water or water-propylene glycol solutions for parenteral injection. Solid form preparations may be converted into liquid preparations shortly before use for either oral or administration. Parenteral forms to be injected intraveneously, intramuscularly or subcutaneously are usually in the form of sterile solutions and may contain tonicity agents (salts or glucose), and buffers. Opacifiers may be included in oral solutions, suspensions and emulsions. Liquid form preparations may also include solutions for intranasal administration.
Aerosol preparations suitable for inhalation may include solutions and solids in powder form, which may be in combination with a pharmaceutically acceptable carrier, such as an inert compressed gas, e.g., nitrogen.
Also included are solid form preparations that are intended to be converted, shortly before use, to liquid form preparations for either oral or parenteral administration. Such liquid forms include solutions, suspensions and emulsions.
The compounds of the invention may also be deliverable transdermally. The transdermal compositions can take the form of creams, lotions, aerosols and/or emulsions and can be included in a transdermal patch of the matrix or reservoir type as are conventional in the art for this purpose.
Preferably, the pharmaceutical preparation is in a unit dosage form. In such form, the preparation is subdivided into suitably sized unit doses containing appropriate quantities of the active component, e.g., an effective amount to achieve the desired purpose.
The effective amount or therapeutically effective amount of compound of the present invention in a unit dose of preparation may be varied or adjusted from about 1 mg to about 1600 mg per day, preferably from about 1 mg to about 1200 mg per day, or about 300 mg to about 1200 mg per day, more preferably from about 1 mg to about 800 mg per day, or about 400 mg to about 800 mg per day and most preferably from about 1 mg to about 100 mg per day from about 400 mg to about 600 mg per day, in single or divided doses, according to the particular compound and particular application.
The actual dosage employed may be varied depending upon the requirements of the patient and the severity of the condition being treated. Determination of the proper dosage regimen for a particular situation is within the skill of the art. For convenience, the total daily dosage may be divided and administered in portions during the day as required.
The amount and frequency of administration of the compounds of the invention and/or the pharmaceutically acceptable salts thereof will be regulated according to the judgment of the attending clinician considering such factors as age, condition and size of the patient as well as severity of the symptoms being treated. The dose of the preferred compounds of formulas I-IV should be chosen to provide steady state plasma concentrations of ribavirin in the range of about 0.1 ug/mL to about 100 ug/mL, preferably in the range of about 0.1 ug/mL to about 50 ug/mL, more preferably in the range of about 1 ug/mL to about 3 ug/mL., and most preferably in the range of about 1.8 ug/mL to about 2.6 ug/mL. Plasma ribavirin concentrations may be determined using high pressure liquid chromatographic material with tandem mass spectrometric detection. The method was validated with respect to linearity, selectivity, precision, accuracy and has a limit of quantitation of 50 microg/mL. A typical recommended daily dosage regimen for oral administration can range from about 1 mg/kg/day to about 100 mg/kg/day, in two to four divided doses.
Ribavirin, 1-xcex2-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide, available from ICN Pharmaceuticals, Inc., Costa Mesa, Calif., is described in the Merck Index, compound No. 8199, Eleventh Edition. Its manufacture and formulation is described in U.S. Pat. No. 4,211,771.
The ribavirin derivatives of formulas I-VIII may be prepared by use of the sequences of steps illustrated in the following Schemes, and in the Examples using the compounds listed hereinafter the Schemes.
In Scheme I, compounds of formula I wherein R5xe2x95x90R5aCOxe2x80x94, R3xe2x95x90R3aCO and R2xe2x95x90H and R5xe2x95x90R5aCOxe2x80x94 and R2xe2x95x90R2aCOxe2x80x94 and R3xe2x95x90H and R5xe2x95x90R5aCOxe2x80x94 and R3xe2x95x90R2xe2x95x90H, are prepared. Compound 110 (ribavirin) and benzaldehyde are treated with ZnCl2 in excess benzaldehyde as solvent at ambient temperature (20 to 25xc2x0 C.) for 24 hrs. to give compound 111. Treatment of 111 with the alkanoyl chloride R5aCOCl in the presence of base e.g. triethylamine (xe2x80x9cTEAxe2x80x9d); or with the carboxylic acid (R5aCOOH) and triethylamine and coupling reagent such as dicyclohexylcarbodiimide (xe2x80x9cDCCxe2x80x9d) produces compound 112. Removal of the acetal protecting group with trifluoroacetic acid:water (9:1, v/v) at ambient temperature for 0.25-2 hrs, preferably about 0.05 hrs. provides compound 113. Compound 113 is converted into a mixture of compounds 114 and 115 by treatment of 113 with R3aCOOH, base and DCC or R3aCOCl and base, e.g., TEA.
Compounds 114 and 115 may be separated by standard chromatographic techniques to provide pure compounds 114 and 115.
In Scheme II, compounds of formula I wherein R5xe2x95x90R3xe2x95x90H and R2xe2x80x94R2aCOxe2x80x94 are prepared from compound 110 (ribavirin). Compound 110 is treated with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane, i.e.,
[(i-Pr)2SiCl]2O, in DMF as solvent in the presence of imidazole for 1-4 hrs. at ambient temperature to give compound 116. Treatment of 116 with R2aCO Cl and base e.g., TEA or R2aCOOH, base and a coupling reagent e.g., DCC for 12-48 hrs. at ambient temperature provides 117. Treatment of 17 with Bu4NF in tetrahydrofuran (xe2x80x9cTHFxe2x80x9d) at ambient temperature for 1-10 hrs. provides compound 118.
Scheme III illustrates the preparation of the compounds of formula I wherein R5xe2x95x90R2xe2x95x90H and R3xe2x95x90R3aCOxe2x80x94 and R5xe2x95x90R3xe2x95x90H and R2xe2x95x90R2aCOxe2x80x94 Ribavirin is treated with trityl chloride or [MeOC6H4(C6H5)2]CCOCl and base, e.g., pyridine in a solvent DMF at ambient temperature for 6-24 hrs. to provide 119. Treatment of 119 with R2a COCl and base or R2a COOH, base and a coupling reagent, e.g., DCC, provides a mixture of compounds 120 and 121. The mixture is separated into the pure compounds by standard chromatographic techniques. Treatment of 120 or 121 with para-toluenesulfonic acid (xe2x80x9cp-TsOHxe2x80x9d) in methanol in the presence of hydrogen and a palladium on charcoal catalyst at ambient temperature for 2-48 hrs. removes the protecting group to give 122 and 123, respectively. p-TsOH salt thereof.
Scheme IV illustrates preparation of the compounds of formula I wherein R5xe2x95x90R5aCOxe2x80x94 or R5xe2x95x90R5a and R3xe2x95x90R2xe2x95x90H. Treatment of ribavirin 110 with R5aCOONxe2x95x90C(CH3)2 in the presence of an enzyme, such as Novo SP 435 lipase at 65xc2x0 C. in a solvent such as THF or dioxane for 12-48 hrs selectively adds R5aCO to the form compound 124. See also Examples 9 to 14. 
Examples for all schemes: 
Xxe2x95x90OH, OAc, NH2, NHCbz, OMe, CN, NO2, F, Cl, Br, and disubstituted benzoates with a combination of these groups xe2x80x98Xxe2x80x99. 
R2aCO, R3aCO, and R5aCO may also be represented by the formulas: 
Yxe2x95x90H, CH3; CH3CH2xe2x80x94; CH3CH2CH2xe2x80x94; Me2CHxe2x80x94; Me2CH2CH2xe2x80x94; CH3CH2CH(Me)xe2x80x94PhCH2xe2x80x94; HOOCCH2CH2xe2x80x94; HSCH2xe2x80x94; HOOCCH2xe2x80x94; MeSCH2CH2xe2x80x94; HOCH2xe2x80x94; 
or Y is H2N(CH2)4xe2x80x94 or CH3CH(OH)xe2x80x94; or a pharmaceutically acceptable salt thereof;
or Y taken together with the xcex1 carbon and N form 
or a pharmaceutically acceptable salt thereof.
or Y taken together with the xcex1 carbon and N form 
wherein R7a is as defined above;
or a phamaceutically acceptable salt thereof.
Examplary 5xe2x80x2-heteroaryl esters of Formulas I and II wherein R5xe2x95x90
The 5xe2x80x2-ester of formula is represented by the formula: 
The following 5xe2x80x2 esters may be prepared as described in Schemes hereinabive, using appropriately protected acids which are readily obtained by procedures well known to one skilled in the art. 
The folowing 5xe2x80x2-3xe2x80x2 cyclic ester (Formula I wherin R2xe2x95x90H) may be prepared using the Schemes herein above and readily available starting materials. 
wherein R101 and R102 are independently H, alkanoyloxy, OR7b or NR6R7b and x=1 or 2
The following 3xe2x80x2-2xe2x80x2 cyclic esters (formula I wherein R5xe2x95x90H) may be made using the Schemes herein above and readily available starting materials. 